Expansible driving core for driving pile shells



840,993 EXPANS'IBLE DRIVING CORE FOR DRIVING PILE SHELLS Filed March 18,1957 H. F. CAUDILL July 1, 1958 5 Sheets-Sheet 1llllllIIJIl/llllllllllllluvll vl/ EXPANSIBLE DRIVING CORE FOR DRIVINGPILE SHELLS Filed March 18, 1957 H. F. CAUDILL July 1, 1958 5Sheets-Sheet 2 IN VEN TOR. wQ/"dfzda,

jaa/@44M EXPANSIBLE DRIVING CORE FOR DRIVING PILE SHELLS Filed March 18,195'7 H. F. CAUDILL s Sheets-sheet s July l, 1958 United States Patent OEXPANSIBLE DRIVING CORE FR DRIVING PILE SHELLS Howard F. Caudill,Arlington Heights, Ill. Application March 18, 1957, Serial No. 646,740

v 18 Claims. (Cl. 61-79) The present invention relates to an expansibledriving core for driving pile shells, and is primarily intended for thedriving of tubular steel pile shells down into the ground through theoperation of a pile driver. These pile shells are preferably ofcylindrical or non-tapered form. After the pile shell has been drivendown to the required depth, the expansible driving core is removedtherefrom, following which the shell is filled with concrete, which maybe reinforced by the addition of reinforcing rods or structural elementsimbedded therein.

For reasons of economy it is frequently desirable to use relativelylight gauge pile shells of cylindrical or non-tapered form which do nothave sufficient wall thickness and sectional area to enable them to bedriven down into the ground under the compression force of driving blowstransmitted solely to their upper ends.

My improved expansible driving core is particularly intended for thedriving of these relatively thin wall cylindrical pile shells, suchbeing made possible by the action of the core expanding outwardly intohigh pressure binding engagement with the inner surface of the pileshell. Thereupon, the driving blows of the pile driving hammer areimparted primarily tothe expanded driving core so that the core drawsthe pile shell down into the ground by a distributed application of thedriving forces along the entire length of the shell, or along the majorportion of its length; My improved drivingv core is applicable to thedriving of either smooth wall pile shell, or helically corrugated shell,or cylindrically corrugated shell.

' One of the principal objects of the invention is to provide animproved expansible core which has a very sturdy, shock-resistingarrangement of cams for eliecting its expansion and contraction; asdistinguished from prior pneumati'ctypes of expansible cores which areexpanded by pneumatic air pressure acting in an elastic expandablecontainer extending lengthwise within the core; or as distinguished frompivoted link or pin and slot expansion actions. V

More specifically in this regard, it is an object of the invention toprovide an expansible driving core which will have animproved'mechanical expanding action, and will also have an improvedmechanical retracting action, both of which actions are attained by verysturdy, shockresisting cams which .can withstand the extremely heavyimpact blows of the pile driving hammer. The inability to withstand thedriving blows of the pile driving hammer has made most of these priorexpansible cores of short life or impractical. j

The positive cam type of mechanical retraction is a particular featureof the present invention because it insures that the core willpositively retract to its original diameter under the action of hoistingpressure ,exerted upwardly through the stem of the core, asdistinguished from gravitational and spring urged retraction whichcharacterizes the prior pneumatic types of expandable cores. Thenon-positive gravitational and spring urged Y f. lCe

retraction in many of these prior expansible cores frequently fails tofree the core from the pile shell after the driving operation.

Another object of the invention is to provide an expansible driving corein which the major portion of the driving blows of the pile drivinghammer is borne by the central stem of the core rather than by theexpansible leaves.

Another object of the invention is to provide an expansible driving corewhich can be quickly and easily repaired in the event of damage arisingas a result of the pile shell striking a boulder, rock ledge or otherunderground obstruction during the driving operation. My improvedcore ischaracterized by a unique construction and arrangement of expansibleouter leaves, which permit a damaged leaf to be quickly and easilyrepaired or substituted. This repair or substitution of a damaged leafcan generally be effected while my improved core structure is suspendedbetween the leads of the pile driving hammer. Thus, repair orsubstitution of a core leaf need not require that the pile drivingoperation be shut down for a substantial period.

Another object of the invention is to provide an expansible driving corewhich has few parts, is simple and inexpensive to construct, and whichdoes not require a source of compressed air for its operation.

Other objects, features and advantages of the invention will appear fromthe following detailed description of certain preferred embodimentsthereof. In the accompanying drawings illustrating such embodiments:

Figure l is a fragmentary vertical axial sectional view of oneembodiment showing the expansible core or mandrel in its retractedcondition, this view corresponding to a section taken on the plane ofthe line 1-1 of Figure 3.

Figure 2 is a similar view showing the mandrel expanded outwardly intothe pile shell, corresponding to a section taken on the plane of theline 2--2 of Figure 4.

Figure 3 is a transverse sectional view taken on the plane of the line 33 of Figure 1, showing the core or mandrel in its retracted condition.

Figure 4 is a transverse sectional view 4taken on the plane of the line4 4 of Fig. 2, showing the core or mandrel in its expanded condition.

Figure 5 is a transverse detail sectional view of the core head, takenon the plane of the line 5--5 of Figure 1.

Figure 6 is ya fragmentary detailed sectional view showing the coreprovided with an outwardly projecting helical rib for engaging in thehelical groove of a helically corrugated pile shell, and Y Figure 7 is afragmentary axial sectional view showing a stepped or multiple-diameterembodiment of my expansible core.

Referring first to Figures 1-5, my improved core structure is designated16 in its entirety, and the pile shell which it is intended to drive isdesignated 17 in its entirety. The main elements of the improved corecomprise an upper driving head 19, a dependingicentral stem portion 20made up of longitudinally extending radial lins 21, and a plurality oflongitudinally extending outer leaves 22 of arcuate outer section.

The driving head 19 is preferably in the form of a forging or steelcasting, having a cushion container 23 projecting upwardly from itsupper surface. This container houses a cushioning block of wood, rubber,or other like cushioning material adapted to cushion the blows of thepile driving hammer striking the driving head 19. The underside of thedriving head is formed with a cup-shaped cylindrical receptacle orsocket 26 into which extends a cylindrical collar or head 28 which isanchored to the upper end of the central vertical stem 20. Formed inthis upper collar 28 of the stem is an annular retaining groove 30.Projecting into this annular groove 30 are a plurality of keepers 32which are removably mounted in horizontal slots 34 angularly spacedaround the side walls of the driving head 19 (Figure 5)..

Projecting outwardly from the driving head 19 at the top and bottomedges of the slots 34 are apertured retainer lugs 36. Each retainingkeeper 32 has an apertured outer portion 3S which is adapted to liebetween the apertured lugs 36, and to receive a removable retainer bolt4 0 which passes down through the apertures in the lugs ,36 'and in thekeeper portions 38. Upon removal of the bolts 40 the keepers 32 may bewithdrawn so as t0 plmit upward removal of the driving head l19 from thecore stern 20. Apertured hoisting lugs 42 project outwardly from theupper edge of the driving head 19 for enabling the driving head to beattached to the pile driving hammer through cables, chains, hooks or thelike so that the head or the entire driving core can be liftedvertically by upward pull exerted on the pile driving hammer. The piledriving blows .are transmitted downwardly from the driving head 19 tothe core stem 20 through the inner abutment face 26 of the socket 26 andthe upper abutment face 28 of the core collar 2S. Attention is directedto the fact that the provision of the keepers 32 engaging lin theannular groove 30 of the core collar establishes a swivel connectionwhich permits horizontal turning rotation of the core stem within thedriving head 19. This swiveling connection permits the core stem 20 torotate relatively to the drivinghead 19 when driving pile shells of thehelically corrugated type, these latter pile yshells imparting asubstantial turning torque to the core stem during the drivingoperation.

Referring now to Figures 3 and 4 showing the construction of the tcorestern 20, it will be seen that .it comprises three or more radiallyextending n bars 21 which have their adjacent .inner edges weldedtogether at 46. These fin bars yextend down the entire length of thedriving core, having their upper ends welded or otherwise secured Vtothe-stem collar 28, and having their lower ends welded to a( circularbottom closure cap 48. This closure cap or head 48 has an annularconical seating surface 48'.

Referring now to the outer leaves 22, there are as many ofthese leavesas thereare radially extending in bars 21, these leaves havingvertically slidable mounting on the iin bars. The leaves consist ofarcuate metallic plates which are preferablyof. a vlength substantiallyequal to the verticall length of their respective tins 21, and whichhave an -outer radius of uniform cylindrical curvature from endvto endcorresponding substantially to the radius of .the inner wall of thecylindrical pile shell 17 to be driven bythe core. Thesangular span ofeach leaf is such thatthe Ileaves can be collapsed into the over-allretracted diameter shown in Figure 3, with a slight space stillremaining between adjacent leaves. Detachably secured tothe `lower endof each `leaf 22 is a sector shaped flange 49 which has an interiorconical seating surface'49 adapted ,to coact with'the exterior conicalseating surface 48 of the .closure head 48 when the core is expanded, asshown in Figure 2. The sectorshaped flanges 49 are detachably secured tothe lower ends of the'leaves 22 by bolts or the like y51 to permitseparation ofthe 'ange from its lrespective leaf when it is desired toremove the leaffrom the core structure for repair or replacement.

Referring now to the cam or wedge apparatus which mechanically extendsand retracts the core leaves'22 relatively to the core stem 20, eachradially extendingiin or rib 21 is notched out lat successive verticallyspaced levels to form upper and lower inwardly extending -radialshoulders 52 and 53, which are joined by the upwardly and outwardlysloping shoulders 54. Weldedalong each sloping shoulder 54 is a cam bar55 which has its upper end terminating at the upper radial shoulder l52,and which has its .lowerend terminating at the lower radial shoulder 53.This cam bar 55 is preferably of circular cross section, and the slopingshoulder 54 of each notch is preferably recessed in arcuate crosssection to receive the circular inner surface of the cam bar 55.

Extending inwardly from each leaf 22 at each of the vertically spacedlevels of the cam bars 55 is a cam follower 56, which is in the form ofa horizontally extending plate of sector profile corresponding to thesector expanse of its respective leaf 22, as viewed in Figures 3 and 4.Each of these cam follower plates 56 is preferably welded along theouter edge to its respective leaf 22, although it will be understoodthat it might be otherwise secured thereto or might even be formedintegral therewith. Cut down centrally from the inner apex of each ofthese cam follower plates is an outwardly extending slot SS whichterminates in a substantially circular hole 60. The side surfaces ofeach slot 58 embrace the side surfaces of the associated iin bar 21, andeach circular hole 60 has sliding .cam follower engagement with theassociated circular cam bar 55. The coaction between the outside surface55 of each cam bar 55 and the outer surface of .the ,associated hole 60establishes the cam relation that expands the leaves 22, and thecoaction between the inside surface 55 of each cam bar and the insidesurface of the associated hole 60 establishes the cam relation thatretracts the leaves 22.

In Figure l, the lower portion of the driving head 19 has been brokenaway to show the spaced relationship between the underside 28 of thecore head 28 and the upper ends of the uppermost cam bars 55. Thisspaced relationship defines horizontal clearance spaces 62 extendingradially outwardly between the Vunderside 28 of the core head 28 and theupper ends of the adjacent cam bars 55, which clearance spaces arenormally closed by the depending skirt portion of the driving head 19.By vremoving the keeper bars 32 and raising the driving head l19relatively to the core head 28, the outer ends of these horizontalclearance spaces 62 can be opened. This permits the uppermost camfollower plate 56 of a damaged leaf 22 to be moved outwardly into aposition clear .of the upper end of the associated cam bar 55, wheneverit is desired to remove a damaged leaf 22 for replacement or repair, Vaswill be later described in greater detail.

conventional tubular p ile shell adapted to be driven by the abovedescribed expansible core is indicated generally a t 17, this pile,shell -usually having a cup shaped driving boot 18 .welded to its lowerend. T he expansible core 16 is lowered into the pile shell `17 when thecore is in its completely retracted condition, with the expansibleleaves 22 all hanging down in their lower inwardly retracted positions,as shown in Figures l and 3. The limit of lower inward movement of theleaves is defined either by the inner surfaces of the leaves strikingthe outer edges of the rradially extending ribs 21, or by the undersurfaces of 'the cam follower plates 56 striking the lower notchingshoulders ,53 cut into the ribs. In this retracted condition, the coreis .lowered into the shell,A or the shell is drawn up :over the core,until the arcuate base llanges 49 at thelower ends of the expansibleleaves 22 strike the bottom of the shell boot 18. Thereupon, continueddownward movement of the core stem 20 relatively to the expansibleleaves 22 causes the cam bars 55Yto exert anV outwardcamniing force onrthe cam follower plates 5,6 for Vforcing the expansible .leaves 22outwardly lagainst thejinner `cylindrical wall ofthe pile shell 17.Substantially at nthe time that the leaves 22 reach the outer limits oftheir expansionmotvement within the pile shell, the bottom closurehead48 at the lower end of the core stem arrives substantially in seatingengagement with the sector shaped flanges 49 at the lower ends of theleaves. Since Vsubstantially all of the driving energy of the piledriving hammer 'is transmitted to the v'pile shell 17 through theinclined cam bars '55 and cam followers 56, it follows that theexpansible core will remain firmly locked within the pile shell from endto end thereof during the entire driving operation. This insures auniform distribution of the pile driving forces over the entire lengthof the pile, thereby permitting a thin wall pile shell to be used.

IIn the operation of `withdrawing the driving core from the -driven pileshell, a hoisting force is transmitted to the upper driving head 19 vofthe core vthrough the apertured hoisting lugs 42. This slides the stem20 and cam bars 55 upwardly `within the cam follower plates 56, with theresult that the inner cylindrical surfaces 55 of the cam bars exert apositive retracting force on the inner surfaces of the cam followerholes 58, thereby positively retracting the expansible leaves 22inwardly to positions where they freely clear the inner wall surface ofthe pile shell. The expansible core is then withdrawn from the pileshell in the collapsed or retracted condition shown in `Figures 1 and 3,and is in immediate readiness for insertion into another pile shell.

To ecectthe removal of a damaged leaf 22 for replacement or repair, theentire driving core 16 is iirst hoisted into an elevated or above-groundposition between the leads of the pile driver, the stem portion 20 ofthe driving core being held in this elevated position as by having itslower end blockedl up on a suitable support. Following this, the sectorshaped flange 49 at the lower end of the damaged leaf is removed; thekeeper bars 32 are released; and the driving head 19 is then raised toopen the outer ends of the clearance spaces 52 which, as previouslydescribed, are defined between the underside 28 of thel coreV head 28and the upper ends of the uppermost cam bars 55. The damaged leaf isthen slid upwardly to bring its uppermost cam follower plate 56 into theopen clearance space 62. This lifting of the leaf to bring the uppermostcam follower plate 56 into the clearance space 62, free of the uppermostcam bar 55, also brings each of `the successively lower cam followerplates 56 into positions free of the upper ends of each of therespective lower cam bars '55. Thereupon, the damaged leaf is free to beremoved laterally or outwardly from the stem portion 20 of the core. Thereplacement of the repaired leaf or of a new leaf is merely a reversalof the foregoing.

In Figures 3 and 4 I have shown the outer surfaces of the expansibleleaves 22 as being provided with outwardly extending projections l70adapted to make interlocking indentations 71 in the inner surfaces ofsmooth walled pile shells 17. These projections 70 are preferably in theform of small metallic cones orhemispheres which are welded to the outersurfaces of the leaves 22. The leaves 22 are expanded outwardly withsufficient force under the driving blows of the hammer to cause theseprojections 7 i) to create the interlocking indentations 71 in the wallof the pile shell, for establishing -a more positive grip of theexpansible core within the shell in the driving operation. Theseprojections 70 clear themselves completely from the indentations 71 inthe positive retraction of the expansi'ble leaves. The projections 70may be arranged in rows or in any other desired pattern on the outersurfaces of the leaves 22. However, a preferred arrangement is toarrange them helically about 8 or l0 inches apart along the line of thehelix and with the helix having the helical pitch of helically weldedsmooth wall pile shell welded along a butt seam, a lap seam or a lockseam, so that-,the button-like projections 7i) will not intersect thehelically welded seam but Vwill act on the shell wall between successiveconvolutions of the helically weldedV seam.

In Figure 6 I have shown a modified construction wherein the outersurfaces of the expansible leaves 22 are provided with segments 74 of anoutwardly projecting helical rib for engaging in the helical groove 75of a helicallyV corrugated pile shell 17a. These helical rib segments'74,may consist of sections of half-round bar or other convex bar coiledas helical segments over the surfaces Vof theV expansible leaves 22 andhaving their ilat surfaces welded to the leaves. Registration of thehelical ribs 74 with the helical grooves 75 can be effected by causingslow relative rotation between the core and the pile shell in the act ofexpanding the core into the shell.

For driving pile shells of the type in which the corrugations extendcircumferentially as distinguished from helically, the convex ribs 74would be welded to the leaves 22 as circumferential segments instead ofhelical segments.

In Figure 7 I have shown a modied embodiment wherein my improvedexpansible core is of stepped or multiple-diameter construction,comprising upper and lower sections 16b, 16e of different diameters, fordriving multiple-diameter pile shells 1717, 17e. The upper section 16dand the lower section 16C are both constructed identically to the singlediameter section 16 shown in Figures 1-4, the only difference being thatthe lower section 16C is of smaller diameter than the upper section16a', the stem 20 and the n bars 21 being stepped down in size in thelower section. As illustrative of typical proportions which may be used,the upper section 16b may be constructed to drive twelve inch pileshells 17b, and the lower section 16C may be constructed to drive teninch pile shells 17e. The adjacent ends of the upper and lower pileshells 17h, 17e may be joined together in any suitable manner, such aswith an overlapping joint provided with an intervening joint sleeve 81welded to both the upper and lower shell sections.

While I have illustrated and described what I regard to be. thepreferred embodiments of my invention, nevertheless it will beunderstood that such are merely exemplary and that numerousmodifications and rearrangements may be made therein without departingfrom the .essence of the invention.

I claim:

l. In an expansible driving core for driving pile shells, thecombination of an axially extending stem, a plurality of expansibleleaves surrounding said stem, a plurality of vertically spaced cams onsaid stem for each leaf, and a plurality of cam followers on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, and said cam followershaving holes embracing outer and inner surfaces of said cam bars,whereby relative axial motion between said stem and said leaves in onedirection effects positive expansion of said leaves into engagement withthe pile shell at the beginning of the driving operation, and wherebyrelative axial motion in the opposite direction eifects positiveretraction of said leaves out of engagement with the pile shell at thecompletion of the driving operation in the core retracting operation.

2. In an expansible driving core for driving pile shells, thecombination of an axially extending stem comprising outwardly projectingns, a plurality of longitudinally extendinn expansible leavessurrounding said stem, a plurality of vertically spaced cams on saidfins for each leaf, and a plurality of cam follower sectors on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly along outer edges of said fins, said cam barsbeing of greater thickness than said ns to present outer and inner camsurfaces, said cam follower sectors comprisingholes embracing said cambars and engaging the outer and inner cam surfaces thereof, wherebydownward motion of said stein within said leaves effects positiveexpansion of said leaves into engagement with the pile shell at thebeginning of the driving operation, and whereby upward motion of saidstem within said leaves effects positive retraction of said leaves outof engagement with the pile shell at the end of the driving operation.

3. In an expansible driving core for driving pile shells, he combinationof an axially extending stem comprising outwardly projecting tins, aplurality of longitudinally extending expansible leaves surrounding saidstem, a plurality of vertically spaced cams on said'fms for each leaf,and a plurality of cam follower sectors on each leaf cooperating withsaid cams, said cams comprising bars of round section sloping upwardlyand outwardly along the outer edges of saidfns, said round cam barsbeing of greater thickness than said fins to present outer and inner camsurfaces, said cam follower sectors having slots embracing said fins andhaving substantially round holes at the outer ends of said slotssurrounding said cam bars and engaging the outer and inner cam surfacesthereof, whereby downward movement of said stem within said leaveseffects positive expansion of said leaves outwardly into engagement withthe pile shell at the beginning of the driving operation, and wherebyupward movement of said stem within said leaves effects positiveretraction of said leaves out of engagement with the pile shell at theend of the driving operation.

4. in an expansible driving core for driving pile shells, thecombination of an axially extending stem, a plurality of expansibleleaves surrounding said stern, a plurality of vertically spaced cams onsaid s tem for each leaf, a plurality of cam followers on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, and said cam followershaving holes embracing outer and inner surfaces of said cam bars,whereby relative axial motion between said stem and said leaves in onedirection elects positive expansion of said leaves into engagement withthe pile shell at the beginning of the driving operation, and wherebyrelative axial motion in the opposite direction effects positiveretraction of said leaves out of engagement with the pile shell in thecore retracting operation, and protuberances on said leaves adapted toeffect a locking t with the interior of said pile shell in the piledriving operation.

5. In an expansible driving core for driving pile shells, thecombination of an axially extending stem comprising outwardly projectingfins, a plurality of longitudinally extending expansible leavessurrounding said stern, a plurality of vertically spaced cams on saidfins for each leaf, and a plurality of cam follower sectors on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly along outer edges of said ns, said cam bars beingof greater thickness than said fins to present outer and inner camsurfaces, said cam follower sectors lcomprising holes embracing said cambars and engagingV the inner and outer cam surfaces thereof, wherebydownward motion of said stem within said leaves effects positiveexpansion of said leaves into engagement with the pile shell at thebeginning of the driving operation, and whereby upward motion of saidstem within said leaves eifects positive retraction of said leaves outof engagement with the pile shell at the end of the driving operation,and spaced protuberances projecting outwardly fromsaid leaves adapted tomake indentations in the inner wall of said pile shell in the operationof driving the shell.

6. In an expansible driving core for driving corrugated pile shells, thecombination of an axially extending stem, a plurality of expansibleleaves surrounding said stem, ribs projecting outwardly from said leavesfor interiitting with the corrugations in said corrugated pile shell, aplurality of vertically spaced cams on said stern for each leaf, and aplurality of cam followers on each leaf, cooperating with said cams,said cams comprising inclined bars sloping upwardly and outwardlyrelatively to said stern, and said cam followers having holes embracinginner and outer surfaces of said cam bars, whereby relative axial motionbetween said stem and lsaid leaves in one direction effects positiveexpansion of said leaves into engagement with the pile shell at thebeginning of the driving operation, and whereby relative axial motion inthe opposite direction effects positive retraction of said leaves out ofengagement with the pile shell in the core retracting operation.

7. In an expansible driving` core for driving spirally corrugated pileshells, the combination of an axially extending stern comprisingoutwardly projectingv fins, a plurality of longitudinally extendingexpansiblevv leaves surrounding said stern, sector shaped ribsprojecting out,- wardly from said leaves in a spiral pattern forinteritting with the spiral'corrugations in said shell, a plurality ofvertically spaced cams on said fins for each leaf, and a plurality ofcam follower sectors on each leaf cooperating with said cams, said camscomprising inclined bars sloping upwardly and outwardly along outeredges of said fins, said cam bars being of greater thickness than saidlins to present outer and inner cam surfaces, said cam follower sectorscomprising holes embracing said cam bars and engaging the outer andinner cam surfaces thereof, whereby downward motion of said stem withinsaid leaves effects positive expansion of said leaves into engagementwith the pile shell at the bginning of the driving operation, andwhereby upward motion of said stern withinl said leaves effects positiveretraction of said leaves out of engagement with the pile shell at theend of the driving operation.

8. in an expansible driving core for driving pile shells, thecombination of an axially extending stem, a plurality of expansibleleaves surrounding said stem, a plurality of vertically spaced cams onsaid stem for each leaf, and a plurality of cam followers on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, and said cam followershaving holes embracing outer and inner surfaces of said cam bars,whereby relative axial motion between said stem and said leaves in onedirection effects positive expansion of said leaves into engagement withthe pile shell at the beginning of the driving operation, and wherebyrelative axial motion in the opposite direction effects positiveretraction of said leaves out of engagement with the pile shell in thecore retracting operation, a driving head at the upper end of said stem,and a swivel connection between said stem and said driving headpermitting relative rotation between said stem and said driving head inthe driving operation.

9. In an expansible vdriving core for driving pile shells, thecombination of an axially extending stem, a driving head at the upperend of said core adapted to receive the driving blows of the piledriving hammer, a swivel collar .on the upper end of said stem rotatablyengaging in a recess in said driving head, said swivel collar having anundercut annular shoulder, releasable retainer means carried by saidhead and adapted to releasably engage under said undercut shoulder forreleasably holding said swivel collar for rotative movement in saiddriving head, a plurality of expansible leaves surrounding said stem, aplurality of vertically spaced cams on said stem for each leaf, and aplurality of cam followers on each leaf cooperating with said cams, saidcams comprising inclined bars sloping upwardly and outwardly relativelyto said stem, and said cam followers having holes embracing outer andinner surfaces of said .cam bars, whereby relative axial motion betweensaid stem and said leaves in one direction effects positive expansion ofsaid leaves into engagement with the pile shell at the beginning ofthedriving operation, and whereby relative axial motion in the oppositedirection effects positive retraction o f said leaves out of engagementwith the pile shell in the core retracting operation.

l0. In an expansible driving core for driving pile shells, thecombination of an axially extending stem, a plurality of expansibleleaves surrounding said stem, a plurality of vertically spaced cams onsaid stem for each leaf, a plurality of cam followers on each leafcooperating with said c ams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, said cam followershaving holes embracing outer and inner surfaces of said cam bars, saidleaves defining a substantially circular opening at the lower end ofsaid core, and a closure head on the lower end of said stemadaptedsnbstantially to close said substantially circular opening in theoperation of driving the pile shell. v

, 11. In apparatus of the class described, the combina-v tion of pileshell means comprising an Upper pile section of relatively largediameter, a lower pile section of relatively small diameter, a steppedmultiple diameter expansible driving core for driving said pile shellmeans, said driving core comprising an upper core section of relativelylarge diameter forfitting within said upper pilersection and a lowercore section of relatively small diameter for fitting within said lowerpile section, an axially extending stem within both core sections, eachof said core sections comprising a plurality of expansible leavessurrounding said stem, a plurality of vertically spaced cams on saidstem for each leaf, and a plurality of cam followers on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, and said cam followershaving holes embracing outer and inner surfaces of said cam bars.

12. In apparatus of the class described, the combination of pile shellmeans comprising an upper pile section of relatively large diameter andalower pile section of relatively small diameter, both pile sectionsbeing cylindrical from end to end, a `stepped multiple diameterexpansible driving core for driving said pile shell means, said drivingcore comprising an upper core section of relatively large diameteriitting within said upper pile section and a lower core section ofrelatively small diameter fitting within said lower pile section, bothsaid upper and lower core sections being cylindrical from end to end, astem extending axially down through said upper and lower core sections,said stem comprising outwardly projecting fins, each of said upper andlower core sections comprising a plurality of longitudinally extendingexpansible leaves surrounding said stem, a plurality of verticallyspaced cams on said fins for each leaf, and a plurality of cam followersectors on each leaf cooperating with said cams, said cams comprisinginclined bars sloping upwardly and outwardly along outer edges of saidfins, said cam bars being of greater thickness than said fins to presentouter and inner cam surfaces, said cam follower sectors comprising holesembracing said cam bars and engaging the outer and inner cam surfacesthereof, whereby downward motion of said stem within said leaves effectspositive expansion of said leaves into engagement with said upper andlower pile sections at the beginning of the driving operation, andwhereby upward motion of said stem within said leaves effects positiveretraction of said leaves out of engagement with said upper and lowerpile sections, at the end of the driving operation.

13. In an expansible driving core for driving pile shells, thecombination of an axially extending stem, a plurality of expansibleleaves surrounding said stem, a plurality of vertically spaced cams onsaid stem for each leaf, a plurality of cam followers on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, said cam followershaving holes embracing inner and outer surfaces of said cam bars, sectorshaped flanges secured to the lower ends of said leaves defining asubstantially circular opening at the lower end of said core, a closurehead on the lower end of said stem adapted substantially to close saidsubstantially circular opening in the operation of driving the pileshell, and means for detachably securing said sector shaped flanges tosaid leaves to permit removal therefrom when substituting leaves.

14. In an expansible driving core for driving pile shells, thecombination of an axially extending stem, a plurality of outwardlyexpansible leaves surrounding said stem, a plurality of verticallyspaced cams on said stem for each leaf, and a plurality of cam followerson each leaf cooperating with said cams, said cams comprising inclinedbars sloping upwardly and outwardly relatively tosaid stem, and said camfollowers having holes embracing outer and inner surfaces of said cambars, whereby relative axial motion between said stem and said leaves inone direction effects positive expansion of said leaves into engagementwith the pile shell at the beginning of the driving operation, andwhereby relative axial motion in the opposite direction effects inwardretraction of said leaves out of engagement with the pile shell at thecompletion of the driving operation, said cam followers being slidableolf the ends of said inclined cam bars, to permit ready removal of anyone of said leaves from said core.

l5. In an expansible drivingr core for driving pile shells, thecombination of an axially extending stem, a plurality of outwardlyexpansible leaves surrounding said stern, a plurality of verticallyspaced cams on said stem for each leaf, a plurality of cam followers oneach leaf cooperating with said cams, said cams comprising inclined barssloping upwardly and outwardly relatively to said stem, and said camfollowers having holes embracing outer and inner surfaces of said cambars, whereby relative axial motion between said stem and said leaves inone direction effects outward expansion of said leaves into engagementwith the pile shell at the beginning of the driving operation, andwhereby relative axial motion in the other direction effects inwardretraction of said leaves out of engagement with the pile shell in thecore retracting operation2 sector shaped flanges at the lower ends ofsaid leaves defining a substantially circular core, means for releasablysecuring said flanges to the lower ends of said leaves, and a closurehead on the lower end of said stem adapted substantially to close saidsubstantially circular opening in the operation of driving the pileshell, any one of said leaves being removable from said core by removingthe sector shaped flange at its lower end and then sliding the leafupwardly to disengage the cam followers of that particular leaf from theupper ends of the inclinedl cam bars associated with that leaf.

16,'In an expansible driving core for driving pile shells, thecombination of an axially extending stem, a driving head at the upperend. of said core adapted to receive the driving blows of the piledriving hammer, a swivel collar on the upper end of said stem rotatablyengaging in said driving head, a plurality of expansible leavessurrounding said stem, a plurality of vertically spaced cams on saidstem for each leaf, and a plurality 0f cam followers on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, and said cam followershaving holes embracing outer and inner surfaces of said cam bars,whereby relative axial motion between said stem and said leaves in onedirection effects outward expansion of said leaves into engagement withpile shell at the beginning of the driving operation, and wherebyrelative axial motion in the opposite direction effects inwardretraction of said leaves out of engagement with'the pile shell in thecore retracting operation, said leaves defining a substantially circularopening at the lower end of said core, and a closure head on the lowerend of said stem adapted substantially to close said circular opening inthe operation of driving the pile shell.

17. In an expansible driving core for driving pile shells, thecombination of an axially extending stem, a driving head at the upperend of said core adapted to receive the driving blows of the piledriving hammer, a swivel collar on the upper end of said stem rotatablyengaging in said driving head, a plurality of expansible leavessurrounding said stem, a plurality of vertically spaced cams on saidstem for each leaf, and a plurality of cam followers on each leafcooperating with said cams, said cams comprising inclined bars slopingupwardly and outwardly relatively to said stem, and said cam followershaving holes embracing outer and inner surfaces of said ca m bars,whereby relative axial motion between said stern and said leaves in onedirection effects outward expansion of said leaves into engagement withpile shell at the beginning of the driving operation, and wherebyrelative axial rn'otion in the opposite direction etects inwardretraction of said leaves out of engagement with the pile shell in thecore retracting operation,r said leaves dening a substantially circularopening at the lower end of said core, and a closure head on the lowerend of said stem adapted substantially to close said circular opening inthe operation of driving the pile shell, any one of said leaves beingremovable from said core for repairs or substitution by sliding the camfollowers of that leaf upwardly beyond the upper ends of the inclinedcam bars associated with that leaf.

18. In an expansible driving core for driving pile shells, thecombination of an axially extending stem, a driving head at the upperend of said core adapted to receive the driving blows of the piledriving hammer, a swivel c ollar on the upper end of said stem rotatablyengaging in a recess in said driving head, said stem comprisingoutwardly projecting fins, a plurality of longitudinally extendingexpansible leaves surrounding said s tem, a plurality of verticallyspaced cams on said fins for each leaf, a plurality of cam followersectors on each leaf cooperating with said cams, said cams comprisingbars of round section sloping upwardly and outwardly along the outeredges of said tins, said round cam bars being of greater thiclness thansaid tins to present outer and inner cam surfaces, said cam followersectors having slots embracing said ns and having substantially roundholes 4at the outer ends of said slots surrounding said cam bars andengaging the outer and inner cam'surfaces thereof,

whereby downward movement of said stem within said' leaves effectspositive expansion of said leaves outwardly into engagement with thepile shell at the beginning ofthe driving operation, and whereby upwardmovement of said stem within said leaves effects positive retraction ofsaid leaves out of engagement with the pile shell at the end of thedriving operation, sector shaped anges at the lower ends of said leavesdefining a substantially circular opening at the lower end of said core,means releasably securing said sector shaped anges to said leaves, and aclosure head on the lower end of said stem adapted substantially toclose said circular opening in the operation of driving the pile shell,any one of said leaves being removable from said core by releasing saidsector shaped flange therefrom and sliding said leaf upwardly until thecam followers thereof clear the upper ends o f the inclined cam barsass0 ciated with that leaf.

No references cited.

